Combination catalyst/coupling agent for furan resin

ABSTRACT

A polymerizable resin composition useful in downhole applications in a subterranean well is disclosed as including a furfuryl alcohol oligomer resin and a polymerization catalyst. The catalyst should be a C 9  to C 15  alkyl benzene sulfonic acid and preferably is a dodecyl benzene sulfonic acid. The polymerizable resin composition may also include an organic diluent selected from C 3  to C 8  alkyl esters, C 1  to C 6  alkyl alcohols; halogenated aromatics and mixtures thereof. Preferably the organic diluent is a C 1  to C 6  alkyl acetate and more preferably the organic diluent is butyl acetate. The polymerizable resin composition may include super-slurper polymers such as copolymers of starch and acrylamides or starch and acrylates. Solid particles may also be included in the polymerizable resin composition. In one embodiment in which the solid particles are sand a consolidated mass of sand particles forms, the consolidated mass having a compressive strength that is at least 50% greater than a similar consolidated mass made using p-toluene sulfonic acid as the polymerization catalyst. At least partial polymerization of the resin occurs at a temperature from about 15° C. (60 F.°) to about 260° C. (500 F.°).

This application claims priority of U.S. Provisional Patent ApplicationNo.: 60/064,052 filed on Nov. 3, 1997.

FIELD OF THE INVENTION

The present invention is generally directed to a polymerizable resincomposition useful in forming a consolidated mass and methods of usingthe polymerizable resin composition downhole in wells.

BACKGROUND

The production of petroleum or natural gas requires a well thatpenetrates at least one petroleum or gas containing subterraneanformation. In doing so, it is not unusual for such wells to penetrateone or more petroleum or gas containing subterranean formations whichalso contain unconsolidated mineral particles, such as sand or gravel.The removal of petroleum, gas, water and other production fluids fromsuch a formation during the production process may cause theunconsolidated mineral particles to enter the well along with theproduction fluids. Such occurrences often lead to a number of difficultand expensive problems.

One problem encountered in some circumstance is that a well will “sandup”, that is to say, the downhole portion of the well fills with sand.Because the downhole portion of the well is sanded-up, furtherproduction of fluid from the formation becomes difficult or impossible.Another problem that may be encountered is when sand is produced alongwith the production fluid. The continuous inclusion of sand in theproduction fluid causes accelerated wear in the pumps and associatedmechanisms utilized during the pumping of the production fluids from thewell due to the abrasive affect of the mineral particles. Yet anotherproblem that may be encountered in such wells is the gradual removal ofmineral particles from the formation around the downhole well areaduring the pumping of production fluid. Over time this gradual removalof mineral particles causes a cavity to form in the subterraneanformation which eventually collapses destroying the well.

The above noted problems and others caused by the inclusion of mineralparticles in production fluids should be well known to one skilled inthe art. Methods have been devised and applied to petroleum wells inorder to reduce or eliminate the production of mineral particles duringthe course of petroleum production. Such methods include the use ofdownhole particle screens and filters, gravel packing methods andtreatment of the formation with various polymerizable resin compositionswhich consolidate the mineral particles into a fluid permeable mass.

In addition to the problems resulting from the production of naturallyoccurring mineral particles, it is sometimes desired to fracture thesubterranean formation to increase the volume of production from thewell. Hydraulic fracturing of the subterranean formation takes placewhen hydraulic pressure applied from the surface, causes the formationto crack or fracture. In order to keep the fracture open, propantmaterials such as sand, glass beads, ceramics, polymer beads and othersuch materials known in the art are pumped into the open fractures. Uponthe start of production, propant material may be dislodged due to theflow of production fluids. The inclusion of propant materials in theproduction fluids act in a similar manner as naturally occurring sand.That is to say the presence of propant material in the production fluidsresults in the premature wear of the down hole pump and other componentsand can result in the “sanding in” of the well.

Another area of concern encountered during petroleum production occurswhen a well is in fluid communication with a subterranean formation thatincludes one or more petroleum producing formations and one or morewater producing formations. Production of petroleum from such a well canresult in the production of both water and petroleum. Because theviscosity of petroleum is typically higher than water, a large volume ofwater may be produced along with the petroleum. The amount of watercontained in the production fluids often referred to as the “water-cut.”Wells with a high water-cut are difficult and expensive to operatebecause a substantial amount of the production volume lost due to thepresence of water. In addition, processes for separating the petroleumfrom the water and disposal of the water in an environmentally soundmanner must be carried out on the surface which increases both capitaland operating costs. Thus it is desirable to minimize the water-cut inthe production fluid pumped to the surface by controlling the flow ofwater into the well from the water producing formations. Methods whichhave been developed to accomplish this goal include downhole separationtechniques and methods of controlling the water flow by sealing off thesource of water with a thermoplastic resin as well as other methodswhich should be known to one skilled in the art.

Yet a third problem encountered by the petroleum industry occurs when anunproductive well is to be abandoned. Before abandonment, a well needsto be effectively and permanently plugged to prevent the migrationfluids from one or more subterranean formation to another subterraneanformation. The plugging of a petroleum well is especially importantbecause the well may penetrate formations containing fresh water thatmay be used for drinking or other purposes. The long term durability andcompressive strength of the materials used to plug wells in preparationfor abandonment is of great concern because of the potential for thecontamination of the fresh water formation by salt water or petroleumformations which the well may also penetrate. One method of preventingsuch migrations is to plug the well with a thermoplastic resin.Typically such plugs include materials to prevent shrinkage or fillersto minimize the amount of thermoplastic resin that is used. If the plugis to be long lasting, it should be able to withstand the conditionsencountered downhole for long periods of time.

One manner of overcoming the above problems is to use thermosettingresins to consolidate the unconsolidated mineral particles or to controlthe production of water from an intervening formation or to permanentlyplug a well prior to abandonment. One of the more successfulthermosetting resins used for these purposes is furfuryl alcohololigomer resin. Furfuryl alcohol oligomer resin is readily polymerizedto form a polymer that is durable in the presence of high temperaturesand caustic substances. Initiation of the polymerization reaction offurfuryl alcohol oligomer resin is temperature dependent and thereaction requires the presence of an acid catalyst. However, care needsto be taken when using such furfuryl alcohol resins in subterraneanwells for these purposes due to the rapid exothermic nature of thepolymerization reaction. It has been reported in the art thatuncontrolled polymerization reactions of furfuryl alcohol resin inpetroleum wells has generated enough heat to cause the subsurfaceexplosion of the well.

In a relevant U.S. Pat. No. 5,285,849 and others noted therein, toluenesulfonic acid is disclosed as being a useful catalyst that gives acontrolled autopolymerization reaction. Despite the success of thisfurfuryl alcohol oligomer resin system, laboratory testing and field usehave identified aspects which need improvement:

1. At formation temperatures below 49° C. (120 F.°), and at formationtemperatures above (270 F.°), the polymerization time for furfurylalcohol oligomer resin becomes unpredictable using toluene sulfonic acidas the catalyst. As a result of this unpredictability, a loss inproduction time occurs.

2. The inclusion of a super-slurper polymer to prevent shrinkage orexpansion of the cured resin or the inclusion of filler materials toincrease volume of a plug material causes unpredictable and excessivelylong curing times when toluene sulfonic acid is used as thepolymerization catalyst.

3. Due to the downhole environment, increased adhesion of the curedfurfuryl resin to the surface of the mineral particles is desired. Anincrease in particle adhesion is readily reflected by an increase thecompressive strength and results in an increase in the durability of theconsolidated particle mass.

SUMMARY OF THE INVENTION

The present invention is generally directed to a polymerizable resincomposition including a furfuryl alcohol oligomer resin and apolymerization catalyst which is a C₉ to C₁₅ alkyl benzene sulfonicacid. In one embodiment the preferred polymerization catalyst isdodecylbenzene sulfonic acid. The resin composition may further includean organic diluent selected from the group including C₃ to C₈ alkylesters, C₁ to C₆ alkyl alcohols, halogenated aromatics and mixturesthereof. In one embodiment the preferred organic diluent is a C₁ to C₆alkyl acetate, more specifically butyl acetate. The polymerizable resincomposition may further include super-slurper polymers or solidparticles. The former include copolymers of starch and acrylamides orstarch and acrylates, while the latter may be selected from the groupincluding sand silica, gravel, glass beads, barite coconut shell orhull, wood chips, wood saw dust and mixtures thereof. When utilizeddownhole to consolidate mineral particles, in particular sand, thepolymerizable resin composition undergoes at least partialpolymerization and forms a consolidated mass of sand particles which hasa compressive strength that is at least 50% greater than a similarconsolidated mass made using previously disclosed polymerizationcatalysts. In one embodiment, the consolidated mass is at leastpartially permeable to fluids. The formulation of the polymerizableresin composition is such that at least partial polymerization occurs ata temperature from about 15° C. (60 F.°) to about 260° C. (500° F.). Thetime required to achieve at least partial polymerization has been foundto depend upon both the polymerization temperature and the amount ofcatalyst within the polymerizable resin composition. In one embodimentthe polymerizable resin composition includes from about 40 to about 90weight percent furfuryl alcohol oligomer resin, from about 5 to about 60weight percent organic diluent and about 0.01 to about 5 weight percentpolymerization catalyst.

The polymerizable resin compositions of the present invention may beused downhole in a petroleum well to prevent the sanding-up of the wellor the inclusion of mineral particles with the production fluids. Insuch cases the polymerizable resin composition is injected into thepetroleum formation followed by a post-flushing of aqueous salt solutionso as to create micro-channels. Upon at least partial polymerization, aconsolidated mass is formed downhole around the well that is at leastpartially permeable to fluids.

The resin compositions of the present invention may also be used in amethod to control the flow of water from subterranean formations intothe well. In such cases the polymerizable resin composition is injectedin the water producing formation and allowed to at least partiallypolymerize. In doing so, the well is effectively isolated from the waterproducing subterranean formation thus preventing the inadvertentproduction of water.

In yet another method of using the polymerizable resin compositions ofthe present invention, the resin compositions are utilized toeffectively seal a well prior to abandonment. In such embodiments, aresin composition is introduced into the well and allowed to at leastpartially polymerize so as to effectively seal the well bore. In somecases super-slurper polymers are included in the resin composition toprevent the shrinkage or expansion of the plug upon full polymerizationor upon changes in the environmental conditions encountered by thedownhole plug. A filler material may also be used to increase the volumeto the resin composition used to form the downhole plug. Examples offiller materials include gravel, rocks, coconut shell or hull, woodchips, wood saw dust and mixtures thereof.

An important aspect of the present invention is that the time requiredfor the resin composition to at least partially polymerize ispredictable and depends upon the curing temperature and the amount ofpolymerization catalyst present in the resin composition. Unlikepreviously utilized polymerization catalysts, the catalysts utilized inpresent invention is not adversely affected by the presence or absenceof super-slurper polymers or filler materials that may be mixed with theresin composition. In addition, the curing time for the resincompositions disclosed herein remain predictable temperatures from about15° C. (60° F.) to about 260° C. (500° F.).

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention is an improvement over the resin systems used ordisclosed in U.S. Pat. Nos. 4,427,069; 4,669,543; 4,800,960; 4,842,072;4,938,287; 5,010,953; 5,199,490; 5,199,492; 5,284,206; 5,285,849;5,293,939; 5,423,381; 5,377,759; and, 5,551,513, the contents of whichare hereby incorporated by reference herein in their entirety.

One aspect of the present invention is a polymerizable resin compositionincluding a polymerizable resin material and a catalyst, the catalystbeing a C₉ to C₁₅ alkyl benzene sulfonic acid. The compositions of thepresent invention are particularly advantageous for use in subterraneanformations in which the temperature is from about 15° C. (60° F.) toabout 260° C. (500° F.).

Any acid catalyzed, polymerizable resinous material which can be used tocoat particles, and then be suspended in the carrier fluid forintroduction into the well bore can be used in our invention. Examplesof such resins include furan resins, furfuryl alcohol resins, phenolresins and other thermoplastic resins that polymerize via a condensationreaction. A particularly preferred polymerizable resin material isfurfuryl alcohol oligomer resin, herein referred to generally asfurfuryl alcohol resin. Furfuryl alcohol resins are readily availablefrom a number of commercial sources. One skilled in the art should knowthat furfuryl alcohol resins are relatively inexpensive polymerizableresins which auto-polymerize upon mixture with acid catalyst and theapplication of heat. Upon curing, the resulting furfuryl alcoholpolymers form an insoluble mass that is highly resistant to chemicalattack and thermal degradation. Commercially obtained furfuryl alcoholresin ordinarily contains about 90 to about 95 percent furfuryl alcoholexamples of which include “QUACOR 1300 FURAN RESIN” TM marketed by Q.O.Chemical or EX18663 resin made by Acme Resin Corporation. The amount offurfuryl alcohol resin may be from about 40 to about 90 percent byweight of the composition.

The furfuryl alcohol resin utilized in the present invention is viscousso in order to permit it to be introduced into the wellbore, pumpeddownhole and into the subterranean formation, it is desirable to reduceviscosity by the addition of a suitable organic diluent. In addition toreducing viscosity, the role of the organic diluent may be to accomplisha relatively complete filling of any void spaces in the formation or toadd density to the polymerizable resin composition. Suitable organicdiluents may be any organic liquid that is soluble in the furfurylalcohol resin and does not accelerate, slow down, inhibit or have otheradverse affects on the polymerization reaction. In one embodiment theorganic diluent is selected from the group including C₃ to C₈ alkylesters, C₁ to C₆ alkyl alcohols; halogenated aromatics and mixturesthereof. In another embodiment the organic diluent is a C₁ to C₆ alkylacetate. The utilization of a hydrolyzable alkyl acetate as the organicdiluent is preferred since the hydrolysis of the alkyl acetate increasesthe extent of polymerization of the furfuryl alcohol resin as isdescribed below. And in yet a third embodiment the organic diluent isbutyl acetate. In situations in which the density of the polymerizableresin composition needs to be increased, a mixture of organic diluentsis used that includes halogenated aromatics. In one such embodiment, amixture of alkyl acetate and bromobenzene is used, however other highdensity halogenated aromatics may be used. When the organic diluent isincluded in the polymerizable resin compositions disclosed herein, theamount may be from 5 to 60 percent by weight of the composition.

As noted above, both an acid catalyst and heat is needed to polymerizethe furfuryl alcohol resin. Suitable catalysts should preferably besoluble in furfuryl alcohol resin and capable of catalyzing theauto-polymerization reaction without other chemical initiators. However,the catalyst must not be too active and cause the premature curing ofthe furfuryl alcohol resin during mixing on the surface, introducinginto the wellbore, and pumping through the well casing to the treatmentsite downhole.

One group of catalysts found to be useful in the present inventioninclude a class of surfactant compounds having a strong acid functionalgroup. It has been found that sulfonic acid functional groups attachedto a hydrophobic groups, such as a long chain alkyl, aryl, or alkylarylgroups, are especially useful. In one embodiment of the presentinvention suitable catalysts include alkyl benzene sulfonic acids inwhich the alkyl group contains from 9 to 15 carbon atoms. Although thepreferred position of the alkyl group on the benzene ring is para to thesulfonic acid group, meta and ortho isomers or a mixture of isomers maybe useful. The preferred structural isomer of the alkyl group is that ofa straight chain alkyl, however isomers in which the alkyl group isbranched may also be useful in the practice of the present invention.Thus in one embodiment a suitable catalyst is selected from the groupincluding nonylbenzene sulfonic acid, decylbenzene sulfonic acid,undecylbenzene sulfonic acid, dodecylbenzene sulfonic acid,tridecylbenzene sulfonic acid, tetradecylbezene sulfonic acid,pentadecyl sulfonic acid, and mixtures thereof. And in a thirdembodiment the catalyst is dodecyl benzene sulfonic acid.

The exact amount of catalyst utilized in any particular formulation willvary depending on the temperature of the subterranean formation and thedesired resin curing time. When utilizing the polymerizable resincompositions of the present invention in the treatment of subterraneanformations to control loose particles or to control water production,the temperature of the formation being treated will essentially be thesame as the resin curing temperature. It has been found that if thetreatment process is to be successful, the uncured polymerizable resincomposition should penetrate the subterranean formation and at leastpartially cure preferably within about 1 to about 2 hours. However it isjust as important that the polymerizable resin composition notprematurely cure in the well string or during the handling on thesurface. Thus, the temperature of the subterranean formation needs to beknown or measured as this will be approximately the same as the resincuring temperature.

One skilled in the art should be able to determine the percent weight ofa dodecyl benzene sulfonic acid (DBSA) catalyst used in the formulationof a polymerizable resin composition by predetermining the resin curingtemperature and then systematically increasing the amount added so as toachieve the desired curing time. As noted above this curing time ispreferably within a range of about 1 to about 2 hours.

As a practical matter and to speed the dissolution of the catalyst inthe furfuryl alcohol resin the catalyst may be dissolved in a minimalamount of C₁ to C₆ alkyl alcohol or C₃ to C₈ alkyl acetate before mixingwith the furfuryl alcohol resin. In one embodiment a methanol solutionsaturated with the catalyst serves this purpose. In another embodiment asaturated solution of catalyst in butyl acetate is used. In a third amixture of organic diluents is used, the organic diluents being selectedfrom the group including C₃ to C₈ alkyl esters, C₁ to C₆ alkyl alcohols;halogenated aromatics and mixtures thereof.

Both polymer and water are generated in the acid catalyzedpolymerization reaction of furfuryl alcohol resin as shown inEquation 1. $\begin{matrix}{{Oligomer}\overset{\quad {acid}\quad}{\rightleftharpoons}{{Polymer} + {H_{2}O}}} & (1)\end{matrix}$

Eventhough the forward reaction which produces polymer and water isfavored, the polymerization reaction will reach a chemical equilibriumand proceed no further. In order to achieve a highly polymerized resinproduct, water should be removed from the system thereby driving thereaction to the right and thus forming a more highly polymerized resin.One way of removing the by-product water is to include an organicdiluent which is readily hydrolyzed under the conditions encountereddownhole. In one embodiment the hydrolysis reaction of an ester isutilized in which the formation of the corresponding alcohol andcarboxylic acid are highly favored as shown in Equation 2.$\begin{matrix}{{RCOOR}^{\prime} + {H_{2}{O\overset{\quad {acid}\quad}{}{RCOOH}}} + {HOR}^{\prime}} & (2)\end{matrix}$

By combining the polymerization reaction with the hydrolysis reaction, ahigh degree of polymerization is achieved. Thus in one embodiment anester is selected so that upon inclusion with the furfuryl resin, theester serves not only as a diluent and solvating agent for the resin,but also hydrolyzes under the conditions suitable for theauto-polymerization reaction of the furfuryl resin. In one embodimentthe ester is a C₃ to C₉ alkyl ester. In another embodiment the ester isa C₁ to C₆ alkyl acetate. And in a third embodiment the ester is butylacetate.

As an alternative embodiment, the polymerizable resin compositionsdescribed herein may also include so called “super-slurper” polymers. Asthe term is used herein, super-slurper polymers are polymers thatfunction so as to minimize the shrinkage or expansion of the curedpolymerized resin compositions described above. In one embodiment,super-slurper polymers may be selected from the group includingcopolymers of starch and acrylamides or starch and acrylates. Unlike theacid catalyst utilized in the prior art, the acid catalysts of thepresent invention are not adversely affected by the inclusion ofsuper-slurper polymers into the polymerizable resin compositionsdescribed herein. As previously noted, when p-toluene sulfonic acid isused as the acid catalyst, the polymerization time becomes unpredictableat all temperatures. This is believe to be due to the interaction orabsorption of the acid catalyst by the super-slurper polymers. However,by utilizing the acid catalysts of the present invention in theformulation of polymerizable resin compositions containing super-slurperpolymer, the polymerization time is essentially unchanged for a widerange of temperatures, that is so say from about 15° C. (60 F.°) toabout 260° C. (500 F.°).

In yet another alternative embodiment, the polymerizable resincompositions described herein may included solid particles. The solidparticles may be mixed with the polymerizable resin compositions so asto coat the solid particles prior to use in the well or the solidparticles may be coated with the polymerizable resin compositions afterthey have been introduced into the well. Such coated particles may beuse in a gravel packing or similar such applications which should beapparent to one of ordinary skill in the art. The solid particles mayalso serve as filler material used to reduce the volume of polymerizableresin composition used in the plugging and abandonment of a well.Suitable solid particles include sand, silica, glass beads, barite,coconut shell or hull, wood chips, wood saw dust and mixtures thereof.One of the benefits of the polymerizable resin compositions disclosedherein is that the inclusion of such solid particles has a minimaleffect on the amount of acid catalyst used in the formulation so as toachieve a predictable polymerization time for any given temperature.This is in contrast to unpredictable nature of the polymerization timein polymerizable resin compositions utilizing the acid catalysts of theprior art, such as p-toluene sulfonic acid, especially when woody orfibrous or other absorbing filler materials are used.

Another aspect of the present invention is a method of consolidatingparticles in a subterranean formation penetrated by a well and being influid communication with the subterranean formation. Generally, themethod includes introducing the formulated polymerizable resin describedabove into the subterranean formation and allowing the polymerizableresin composition to at least partially polymerize so as to form aconsolidated mass of particles around the well.

If a porous consolidated mass of particles is desired, the method mayfurther include flushing an aqueous salt solution into the subterraneanformation prior to allowing the polymerizable resin to at leastpartially polymerize. As used herein this flushing with an aqueous saltsolution is referred to as a “post-flush”. The purpose of post-flushingis to coat the mineral particles with polymerizable resin composition sothat upon polymerization a fluid permeable consolidated mass of mineralparticles is formed in the subterranean formation around the well.

An alternative embodiment of the present aspect of the present inventionincludes determining the temperature of the subterranean formation andformulating a polymerizable resin composition with sufficient acidcatalyst so that the polymerizable resin composition will polymerize ina predictable time period. This sub-embodiment further includesintroducing the polymerizable composition into the well bore and pumpingthe polymerizable resin composition down hole and into a subterraneanformation wherein at least partial polymerization of the polymerizableresin composition takes place thus forming a consolidated mass about thewell. If a fluid permeable consolidated mass of particles is desired,then prior to allowing the polymerizable resin composition to at leastpartially polymerize an aqueous salt solution is pumped downhole andflushed through the resin saturated area of the subterranean formation.As noted above, this post flushing coats the unconsolidated mineralparticles with the polymerizable resin composition which uponpolymerization forms a fluid permeable consolidated mass of mineralparticles in the subterranean formation around the well.

In a third alternative embodiment of the present method, solid particlesmay be coated on the surface with the polymerizable resin compositiondisclosed above and subsequently delivered downhole. In one suchembodiment gravel or glass beads are coated with a polymerizable resincomposition formulated so as to contain a suitable amount of acidcatalyst. The resin coated gravel or glass beads are introduced into thewell and pumped downhole and into the subterranean formation and thepolymerizable resin composition is allowed to at least partiallypolymerize thus forming a consolidated mass of particles in thesubterranean formation around the well. If a fluid permeable mass isdesired downhole, post flushing with an aqueous salt solution is carriedout prior to the polymerization of the polymerizable resin composition.This subembodiment should be recognized by one of ordinary skill in theart as “gravel packing” the well.

Yet another embodiment of the present method is possible when a well isto be plugged in preparation for abandonment. In one such alternativeembodiment super-slurper polymers are mixed into the polymerizable resincomposition as is described above. The polymerizable resin compositionis then introduced into the wellbore and pumped downhole to the verticallocation in the well where the plug is desired. The vertical location ofthe plug in the well is determined by using conventional pluggingmethods and equipment which should be well known to one of ordinaryskill in the art. The polymerizable resin composition is allowed to atleast partially polymerize there by forming a solid thermoplastic resinplug which effectively seals the well. In some wells a single plug isall that is needed. In other wells a plurality of such plugs may be usedto isolate different subterranean formations. In another suchalternative embodiment a filler material is mixed with the polymerizableresin composition just prior to introducing the polymerizable resincomposition into the well. Examples of such filler materials include,gravel and rocks, coconut shells and hulls, wood chips, wood saw dust orany other inexpensive material that is suitable. The role of such fillermaterials is to reduce the amount of polymerizable resin compositionthat is needed to fill and effectively plug the well.

The following examples are included to demonstrate illustrativeembodiments of the invention. It should be appreciated by those of skillin the art that the techniques disclosed in the examples which followrepresent techniques discovered by the inventors to function well in thepractice of the invention, and thus can be considered to constitutepreferred modes for its practice. However, those of skill in the artshould, in light of the present disclosure, appreciate that many changescan be made in the specific embodiments which are disclosed and stillobtain a like or similar result without departing from the scope of theinvention.

EXAMPLE 1

Polymerizable resin compositions with either 2% or 4% weight of dodecylbenzene sulfonic acid (DBSA) were prepared by mixing measured amounts ofDBSA into a mixture of about 80 parts by weight furfuryl alcohol resinand about 20 parts by weight butyl acetate. A sufficient amount of theresulting homogeneous mixtures were poured into disposable syringes,typically 5 ml in volume, packed with about 2.6 cm (1 inch) of 20-40mesh Ottawa sand so as to saturate the sand with resin. If a fluidpermeable sample was desired, the resin coated sand was post-flushedwith a saturated aqueous sodium chloride solution. Typically the volumeof the post-flush aqueous solution was about three time the volume ofthe syringe use (i.e. 15 ml). The samples were then placed in an oven at93° C. (200° F.) until hard.

The sample with 4% DBSA had a curing time of less than 1 hour while thatof the sample with 2% DBSA had a curing time of about 2 hours. Oneskilled in the art should recognize and be able to empirically determineby routine experimentation the relationship between the amount of DBSAcatalyst used and the curing temperature of the sample affect the settime of the resin.

EXAMPLE 2

A number of polymerizable resin compositions with various concentrationsof dodecyl benzene sulfonic acid (DBSA) were prepared by mixing measuredamounts of DBSA into a mixture of about 80 parts by weight furfurylalcohol resin available from commercial sources and about 20 parts byweight butyl acetate. The amount of DBSA for any particular formulationis given below in Table 1. A sufficient amount of the resultinghomogeneous mixtures were poured into disposable syringes, typically 5ml in volume, packed with about 2.6 cm (1 inch) of 20-40 mesh Ottawasand so as to saturate the sand with resin. If a fluid permeable samplewas desired, the resin coated sand was post-flushed with a saturatedaqueous sodium chloride solution. Typically the volume of the post-flushaqueous solution was about three time the volume of the syringe use(i.e. 15 ml). The samples were then placed in an oven at thetemperatures noted below in Table 1 and the set time determined. Asample was consider to be hardened when pressing on the sample indicatesno substantial deformation of the sample. A representative sample ofsample temperature and approximate set time are given in Table 1:

TABLE 1 Sample Amount of DBSA* Temperature Approximate Set Time Number(% weight) ° C. (F°) (hours) 1 4 27 (80)  6-21 2 2 27 (80)  about 56 3 493 (200) less than 1 4 2 93 (200) 2 5 2.1 49 (120) about 8 6 2.2 49(120) about 8 7 2.3 49 (120) about 8 *DBSA = dodecyl benzene sulfonicacid

As should be apparent to one of ordinary skill in the art in view of theabove data, the amount of DBSA catalyst used and the curing temperatureof the sample affect the set time of the resin. Further one of ordinaryskill in the art should be able to use the above example to vary theamount of catalyst present in the resin composition and determine theset time at a predetermined temperature. Thus a matrix of values forcure time, curing temperature and amount of catalyst can be created anused to vary the formulation of the resin composition to suit theapplication desired.

EXAMPLE 3

In the present example the use of dodecyl benzene sulfonic acid as thepolymerization catalyst is compared with toluene sulfonic acid.

A polymerizable resin composition utilizing dodecyl benzene sulfonicacid as the polymerization catalyst was prepared by mixing 80 parts byweight of the furfuryl alcohol resin utilized in Example 1 and 20 partsby weight of butyl acetate into which 2% by weight of dodecyl benzenesulfonic acid was added as the catalyst. This polymerizable resincomposition is referred to below as polymerizable resin composition A.

A polymerizable resin composition utilizing p-toluene sulfonic acid asthe polymerization catalyst was prepared by mixing 80 parts by weight ofthe furfuryl alcohol resin with 20 parts by weight of butyl acetate intowhich 2% by weight of p-toluene sulfonic acid was added as thepolymerization catalyst. This polymerizable resin composition isreferred to below as resin composition B.

Either resin composition A or resin composition B was used prepare sandpacks for comparative testing of compressive strength as describedbelow.

Preparation of Compressive Strength Test Samples: A disposable plasticsyringe (5 ml) was filled with 20-40 Ottawa Sand so as to contain atleast about 2.6 cm (1 inch) of sand. Sufficient amounts of the freshlyprepared polymerizable resin composition was poured into the syringecontaining the sand so as to saturate the sand. If the sand pack is tobe at least partially permeable to fluids a saturated aqueous solutionof sodium chloride is post-flushed through the resin/sand containingsyringe. Typically the volume of solution used to post flush the resinis at least three times that of the capacity of the syringe. Theresin/sand containing syringe is hardened in an oven held at about 65°C. (150° F.) overnight. The test sample is readily removed from thesyringe upon cooling and is used to determine compressive strength.

Compressive Strength Test: An adequately shielded press that has a scaleto determine the applied pressure may be used. In the present example ahydraulic press was used. The pressure at which the test sample beginsto exhibits cracking is considered the compressive strength of thesample. The compressive strength of a test samples made with resincomposition A were measured in relation to the compressive strength oftest samples made with resin composition B. It was found that thesamples using resin composition A had higher compressive strengths thatthe samples using resin composition B. In addition upon microscopicexamination of the sand particles it was observed that the sandparticles were more uniformly coated with resin containing DBSA as acatalyst than were the sand particles coated with the resin using TSA asthe catalyst.

In view of the above, one of ordinary skill in the art should understandthat one illustrative embodiment of the present invention includes apolymerizable resin composition including a furfuryl alcohol oligomerresin and a polymerization catalyst. The catalyst should be a C₉ to C₁₅alkyl benzene sulfonic acid and preferably the alkyl benzene sulfonicacid is dodecyl benzene sulfonic acid. The polymerizable resincomposition may further include an organic diluent selected from C₃ toC₈ alkyl esters, C₁ to C₆ alkyl alcohols; halogenated aromatics andmixtures thereof. Preferably the organic diluent is a C₁ to C₆ alkylacetate and more preferably the C₁ to C₆ alkyl acetate is butyl acetate.The illustrative polymerizable resin composition may also include asuper-slurper polymer, for example polymers selected from copolymers ofstarch and acrylamides or starch and acrylates. In addition, solidparticles may be included into the illustrative polymerizable resin.Such solid particles may be selected from sand, silica, gravel, glassbeads, barite, coconut shell or hull, wood chips, wood saw dust, similarsuch inert filler materials and mixtures thereof. When the solidparticles are sand and upon at least partial polymerization of thepolymerizable resin composition a consolidated mass of sand particlesshould form in which the consolidated mass has a compressive strengththat is at least 50% greater than a similar consolidated mass made usingp-toluene sulfonic acid as the polymerization catalyst. One of skill inthe art should appreciate that the consolidated mass of sand particlesmay be made to be at least partially permeable to fluids, such as water,oil or other production fluids by the use of a “post-flush” fluid. Atleast partial polymerization of the resin should take place at atemperature from 15° C. (60 F.°) to 260° C. (500 F.°) and preferablysuch polymerization should occur in about 1 to about 2 hours. Aspreviously noted, the temperature and the time for polymerization arefunction of the amount of catalyst present in the resin formulation.Upon the determination of one, for example time, the amount of catalystutilized depends as a function of the temperature. The determination ofthe exact amount of catalyst utilized thus may be made by fixing eithertime or temperature and systematically varying the amount of catalystused until the desired result is achieved.

Another illustrative embodiment of the present invention includes apolymerizable resin composition for use downhole in a subterranean well.Such an illustrative resin composition should include a furfuryl alcohololigomer resin, an organic diluent and a C₉ to C₁₅ alkyl benzenesulfonic acid. In one preferred embodiment, the organic diluent is a C₁to C₆ alkyl acetate and the alkyl benzene sulfonic acid is dodecylbenzene sulfonic acid. The polymerizable resin composition should beformulated so that at least partial polymerization of the resincomposition occurs at a temperature from about 15° C. (60 F.°) to about260° C. (500 F.°). In one illustrative embodiment, the amount offurfuryl resin is from 40 to 90 percent weight, the amount of theorganic diluent is from 5 to 60 percent weight and the amount of the C₉to C₁₅ alkyl benzene sulfonic acid is from 0.01 to 5 percent weight. Thepolymerization resin may also include solid particles such as sand,silica, gravel, glass beads, barite, coconut shell or hull, wood chips,wood saw dust and mixtures thereof. When the solid particles are sandthe resin should be formulated so that upon at least partialpolymerization a permeable consolidated mass of solid particles forms.This permeable consolidated mass should be at least partially permeableto fluids and have a compressive strength that is at least 50% greaterthan a similar consolidated mass made using p-toluene sulfonic acid asthe polymerization catalyst.

A person of ordinary skill in the art should also appreciate that thepresent invention includes the use of the present invention in a methodfor consolidating the formation area surrounding the downhole producingzone of an oil or gas well. Such an illustrative method would include amethod for consolidating particles in a subterranean formationpenetrated by a well in which the well is in fluid communication with atleast a portion of the subterranean formation. Such an illustrativemethod may include: introducing a polymerizable resin composition intothe subterranean formation and allowing the polymerizable resincomposition to at least partially polymerize thus forming a consolidatedmass of particles around the well. The polymerizable resin compositionshould include a furfuryl alcohol oligomer resin and a polymerizationcatalyst, the catalyst preferably being a C₉ to C₁₅ alkyl benzenesulfonic acid and more preferably the catalyst is dodecyl benzenesulfonic acid. In one illustrative embodiment the polymerizable resincomposition further includes an organic diluent preferably selected fromC₃ to C₈ alkyl esters, C₁ to C₆ alkyl alcohols; halogenated aromaticsand mixtures of these compounds. Preferably the organic diluent is a C₁to C₆ alkyl acetate and more preferably the organic diluent is butylacetate. The illustrative polymerizable resin composition may alsoinclude a super-slurper polymer. Such super-slurper polymers may becopolymers of starch and acrylamides or starch and acrylates or anyother similar such polymer that absorbs water. Solid particles may alsobe included in the illustrative polymerizable resin composition andpreferably such solids are selected from sand, silica, gravel, glassbeads, barite, coconut shell or hull, wood chips, wood saw dust andmixtures of these solids. The mixture of components in the illustrativeresin should preferably include furfuryl resin in an amount from about40 to about 90 percent weight, organic diluent in an amount from about 5to about 60 percent weight and C₉ to C₁₅ alkyl benzene sulfonic acid inan amount from about 0.01 to about 5 percent weight. The illustrativemethod may further include flushing an aqueous salt solution into thesubterranean formation prior to allowing the polymerizable resincomposition to at least partially polymerize thus forming a consolidatedmass of particles around the well that is at least partially permeableto fluids. The inclusion of the flushing step should preferably resultin a consolidated mass that is at least partially permeable to fluidshas a compressive strength that is at least 50% greater than a similarconsolidated mass made using p-toluene sulfonic acid as thepolymerization catalyst.

While the compositions and methods of this invention have been describedin terms of preferred embodiments, it will be apparent to those of skillin the art that variations may be applied to the process describedherein without departing from the concept and scope of the invention.All such similar substitutes and modifications apparent to those skilledin the art are considered to be within the concept and scope of thisinvention as defined by the following claims.

What is claimed is:
 1. A method for consolidating particles in asubterranean formation penetrated by a well, the well being in fluidcommunication with at least a portion of the subterranean formationcomprising: introducing a polymerizable resin composition into thesubterranean formation, the polymerizable resin composition including afurfuryl alcohol oligomer resin and a polymerization catalyst, thecatalyst being a C₉ to C₁₅ alkyl benzene sulfonic acid, and allowing thepolymerizable resin composition to at least partially polymerize thusforming a consolidated mass of particles around the well.
 2. The methodof claim 1 wherein the alkyl benzene sulfonic acid is dodecyl benzenesulfonic acid.
 3. The method of claim 1 wherein the polymerizable resincomposition further includes an organic diluent selected from the groupconsisting of C₃ to C₈ alkyl esters, C₁ to C₆ alkyl alcohols;halogenated aromatics and mixtures thereof.
 4. The method of claim 3wherein the organic diluent is a C₁ to C₆ alkyl acetate.
 5. The methodof claim 4 wherein the C₁ to C₆ alkyl acetate is butyl acetate.
 6. Themethod of claim 3 wherein the polymerizable resin composition furtherincludes a super-slurper polymer selected from the group consisting ofcopolymers of starch and acrylamides or starch and acrylates.
 7. Themethod of claim 3 wherein the solid particles are selected from thegroup consisting of sand, silica, gravel, glass beads, barite, coconutshell or hull, wood chips, wood saw dust and mixtures thereof.
 8. Themethod of claim 1 further comprising flushing an aqueous salt solutioninto the subterranean formation prior to allowing the polymerizableresin composition to at least partially polymerize thus forming aconsolidated mass of particles around the well that is at leastpartially permeable to fluids.
 9. The method of claim 8 wherein theconsolidated mass that is at least partially permeable to fluids has acompressive strength that is at least 50% greater than a similarconsolidated mass made using p-toluene sulfonic acid as thepolymerization catalyst.
 10. The method of claim 1 wherein thesubterranean formation has a temperature from 15° C. (60 F.°) to 260° C.(500 F.°).
 11. The method of claim 3 wherein the amount of furfurylresin is from 40 to 90 percent weight, the amount of the organic diluentis from 5 to 60 percent weight and the amount of the C₉ to C₁₅ alkylbenzene sulfonic acid is from 0.01 to 5 percent weight.
 12. Apolymerizable resin composition for use downhole in a well comprising afurfuryl alcohol oligomer resin, a C₃ to C₈ alkyl ester and a C₉ to C₁₅alkyl benzene sulfonic acid polymerization catalyst.
 13. Thepolymerizable resin composition recited in claim 12 wherein the organicdiluent includes a C₁ to C₆ alkyl acetate and the alkyl benzene sulfonicacid is dodecyl benzene sulfonic acid.
 14. The polymerizable resincomposition recited in claim 13 wherein at least partial polymerizationof the resin composition occurs at a temperature from 15° C. (60 F.°) to260° C. (500 F.°).
 15. The polymerization resin recited in claim 14further comprising solid particles, the solid particles being selectedfrom the group consisting of sand, silica, gravel, glass beads, barite,coconut shell or hull, wood chips, wood saw dust and mixtures thereof.16. The polymerizable resin composition recited in claim 15 wherein thesolid particles are sand and upon at least partial polymerization apermeable consolidated mass of solid particles forms that is at leastpartially permeable to fluids, the permeable consolidated mass having acompressive strength that is at least 50% greater than a similarconsolidated mass made using p-toluene sulfonic acid as thepolymerization catalyst.
 17. The polymerizable resin composition ofclaim 12 wherein the amount of furfuryl resin is from 40 to 90 percentweight, the amount of the organic diluent is from 5 to 60 percent weightand the amount of the C₉ to C₁₅ alkyl benzene sulfonic acid is from 0.01to 5 percent weight.
 18. The polymerizable resin composition of claim 17wherein the organic diluent is a C₁ to C₆ alkyl acetate and the alkylbenzene sulfonic acid is dodecyl benzene sulfonic acid.